Environmental news from California and beyond

[Updated at 9:43 a.m.: The Obama administration has given BP permission to move ahead with its much-anticipated attempt to plug the Gulf of Mexico oil leak.

From the Joint Information Center: "Federal On-Scene Coordinator Rear Admiral Mary Landry, acting on the validation of government scientists and in consultation with the National Incident Commander Admiral Thad Allen, has granted approval for BP to begin proceeding with their attempt to cap the well using the technique known as the 'top kill.'

This expedited step provides the final authorization necessary to begin the procedure."]

Engineers worked through the night to gauge pressure and run other diagnostic tests associated with the billowing oil. In a sign of the critical importance of the effort, Energy Secretary Steven Chu -- a Nobel-winning physicist -- has personally joined the diagnostic team in Houston.

An administration official said Wednesday morning that Chu and others were meeting to discuss the test results and help inform BP executives, who ultimately will decide whether to move ahead or call off the attempt.One of the engineers involved in the project wrote on his Twitter account that the BP executives had delayed the effort due to concerns over high flow rates in the well, and had ordered another round of tests.The "top kill" plan would be an attempt to overpower the flow of oil by pumping drilling fluid -- and eventually concrete -- at high pressure into the well. Several hundred engineers in Houston have prepped for the effort for weeks.

If executed incorrectly, however, the top kill could blow the fail-safe systems, dramatically increasing the flow of oil.